Retrospective analysis of 18F-FDG PET/CT for staging asymptomatic breast cancer patients younger than 40 years

Abstract

National Comprehensive Cancer Network guidelines consider (18)F-FDG PET/CT for only clinical stage III breast cancer patients. However, there is debate whether TNM staging should be the only factor in considering if PET/CT is warranted. Patient age may be an additional consideration, because young breast cancer patients often have more aggressive tumors with potential for earlier metastases. This study assessed PET/CT for staging of asymptomatic breast cancer patients younger than 40 y.

Methods: In this Institutional Review Board-approved retrospective study, our hospital information system was screened for breast cancer patients younger than 40 y who underwent staging PET/CT before any treatment. Patients with symptoms or conventional imaging findings suggestive of distant metastases or with prior malignancy were excluded. Initial stage was based on physical examination, mammography, ultrasound, and breast MR imaging. PET/CT was then evaluated to identify unsuspected extraaxillary regional nodal and distant metastases.

Results: One hundred thirty-four patients with initial breast cancer stage I to IIIC met inclusion criteria. PET/CT findings led to upstaging to stage III or IV in 28 patients (21%). Unsuspected extraaxillary regional nodes were found in 15 of 134 patients (11%) and distant metastases in 20 of 134 (15%), with 7 of 134 (5%) demonstrating both. PET/CT revealed stage IV disease in 1 of 20 (5%) patients with initial clinical stage I, 2 of 44 (5%) stage IIA, 8 of 47 (17%) stage IIB, 4 of 13 (31%) stage IIIA, 4 of 8 (50%) stage IIIB, and 1 of 2 (50%) stage IIIC. All 20 patients upstaged to stage IV were histologically confirmed. Four synchronous thyroid and 1 rectal malignancies were identified.

Conclusion: PET/CT revealed distant metastases in 17% of asymptomatic stage IIB breast cancer patients younger than 40 y. Although guidelines of the National Comprehensive Cancer Network recommend against systemic staging in patients with stage II disease, our data suggest that PET/CT might be valuable in younger patients with stage IIB and III disease. Use of PET/CT in younger patients has the potential to reduce the morbidity and cost of unnecessary therapies in young breast cancer patients.

Keywords: FDG; PET; breast cancer; metastases; staging.

FIGURE 1

A 29-y-old woman with clinical stage IIA breast cancer upstaged to stage IV by ¹⁸F-FDG PET/CT. Axial PET/CT images demonstrated known primary left breast cancer (arrowhead) (A), previously unknown osseous metastasis (solid arrow) (B), and previously unknown liver metastasis (dashed arrow) (C) proven by biopsy. (D) Maximum-intensity-projection PET gives overview of all lesions.

FIGURE 2

A 32-y-old woman with clinical stage IIB breast cancer upstaged to stage IV by ¹⁸F-FDG PET/CT. (A) Maximum-intensity-projection PET demonstrated known primary left breast cancer (arrowhead), known axillary nodal metastases (short arrows), and 2 foci of ¹⁸F-FDG uptake in midline of body (long arrows). Axial PET/CT (B) and axial CT (C) through chest demonstrated primary breast cancer (arrowhead) and localized 1 of the midline foci to sternum without osteolytic or osteoslcerotic correlate on CT (long arrows). Biopsy of sternum demonstrated osseous metastasis unknown before PET/CT. Second midline focus was subsequently proven to be sacral metastasis (not shown).

FIGURE 3

A 35-y-old woman with clinical stage IIIA breast cancer upstaged to stage IV by ¹⁸F-FDG PET/CT. (A) Maximum-intensity-projection PET demonstrated known primary left breast cancer (arrowhead), known axillary nodal metastases (short arrow), previously unknown internal mammary node (solid long arrow), and focus of ¹⁸F-FDG uptake in region of lumbar spine (dashed long arrow). Axial PET/CT (B) and CT (C) localize latter focus to L3 vertebral body without osteolytic or osteoslcerotic correlate on CT (dashed long arrows). Biopsy of L3 lesion demonstrated osseous metastasis and stage IV disease unknown before PET/CT. Given stage IV disease, biopsy of internal mammary nodal focus was unnecessary.

FIGURE 4

A 38-y-old breast cancer patient with internal mammary nodal metastasis detected by ¹⁸F-FDG PET/CT and verified by imaging follow-up. Axial PET/CT (A) and maximum-intensity-projection PET images (B) demonstrate known primary left breast cancer (arrowheads), known left axillary node (short arrows), and previously unknown left internal mammary node (long arrows). Axial PET/CT (C) and maximum-intensity-projection PET images (D) following 5 mo of neoadjuvant chemotherapy demonstrated complete resolution of all ¹⁸F-FDG–avid lesions. Findings on imaging follow-up were considered validation of extraaxillary nodal metastasis.